Available for iOS, the app lets you add Hollywood-style special effects to videos you've shot with your iPhone or iPad.

What kinds of effects? Suppose you're making a movie that involves blowing up a car (as all good movies should). Action Movie FX includes a missile-attack sequence that ends with a gorgeous fiery explosion. All you do is record at least 5 seconds of video (in this case, footage of your car), then wait for the app to render the effect.

When it's done, you'll see that missile sequence overlaid on the clip you just shot. If the timing didn't work exactly right, you can adjust it in "postproduction." And you can save the clip to your Camera Roll for use elsewhere; it's not locked into Action Movie FX.

Version 2.5 brings a host of worthwhile improvements, starting with free HD upgrades for all previous effects. You also get three free exclusive, licensed FX from "Star Trek Into Darkness": Enterprise Flyby, Phaser Fight, and Photon Torpedoes. These aren't lame animations, either: They're as realistically rendered as scenes from the movie.

For a mere 99 cents, you can also purchase a "Star Trek" pack with two additional effects: Transporter and Warp. The former is especially cool: Now you can "beam" the stars of your movie to other locations, with a look that's as polished and professional as if you'd hired an FX house.

And this I especially love: Bad Robot Interactive donates all the proceeds from that pack to The Mission Continues, a charity that helps post-September 11 veterans.

The app includes five other free effects (up from four in the previous version), plus nine other nifty two-packs priced at 99 cents each. And if you're a graphics-artist whiz, you can submit your own special effects for possible inclusion in a future app update. Bad Robot Interactive will pay the winner a "reasonable" fee for the work.

I'm still hoping to see the app evolve with more editing options, like extending a sequence or adding slow-motion effects. But it's already a great way to add some incredibly cool visuals to your movie, for a price that's hard to beat.